1. Field of the Disclosure
The disclosure herein relates generally to a method and apparatus for generating light from a laser source for use in visual display applications.
2. Description of the Related Art
Viewers generally evaluate display systems based on several criteria such as image size, resolution, contrast ratio, color purity, and brightness. Image brightness is an important metric since the available brightness can limit the size of a projected image and also because it can control how well the image can be seen in high levels of ambient light. Brightness of a projected image typically can be increased by increasing the size of the light source used to form the image. However, increasing the size of the light source also can increase the cost, size, and weight of the display system. Additionally, larger light sources generate additional heat that also is not desirable.
Another approach has been to use an inherently bright light source, such as a laser. A laser produces a highly monochromatic beam of light. In one such system a separate diode pumps light into separate glass/crystal rods. Such systems are commonly referred to as solid-state illuminators. Additional elements, such as frequency-doublers, polarizing elements and output couplers are used to provide continuous light of each primary color. Some such systems utilize three spaced-apart diodes, which can occupy substantial space and can be relatively inefficient. Additionally, the same amount of current is typically provided to each diode. The various components, such as solid-state rods, however, can have different gains or can develop different gains over time, resulting in unbalanced light output from the different lasers. Thus, there is a need for an improved solid-state illuminator that addresses at least some of the above-noted deficiencies.